MCQ on LED ( Light Emitting Diode MCQ )
If you are looking for LED Multiple Choice Questions. Here we collected some important MCQs on LED pdf. The LED mcqs pdf for class 12th and engineering students included in this page have been selected based on the popular questions asked in various competitive exams over the years.
Multiple Choice Questions on LED
1. Light emitting diodes emits light when it is in______________
(a) forward biased
b) reverse biased
c) zero biasing
d) infinite biasing
Answer: A
2. In LED's light energy is emitted when_________
a) electrons falls from conduction band into holes is valence band
b) electrons falls from valence band into holes is conduction band
c)electrons and holes recombine in forbidden energy gap
(d) both 'b' and 'c'
Answer: A
3. The nature of light emitted by LEDs depends upon
a) nature of material used in LEDs
b) the difference in energy levels of material used
c) both 'a' and 'b
d) neither'a' nor 'b'
Answer: C
4. Limiting resistance(R) is used in LED for_______
a) controlling current flowing through LED
b) controlling colour of emitted light
c) both'a' and 'b
d) neither a nor b
Answer: A
5. LEDs of GaAs and GaAsP releases energy in_________
a) infra-red and visible region respectivelyy
b) visible and infra-red region respectively
c) visible and ultra-violet region respectively
d) ultra-violet and infra-red region respectively
Answer: A
6. LEDs are most popularly used because_________
a) it operates at high voltages
b) its power consumption is less
c)it is cheap and easy to handle
d) both 'b' and 'c'
Answer: D
7. LEDs are used in______
a) visual display
b) decorative lamps in photo frame
c) both 'a' and 'b'
d) neither 'a' nor 'b'
Answer: C
8. What is full form of LED ?
(a) Low Emitting Diode
(b) Light Emitting Diode
(c) Light Emitting Data
(d) Light Encounter Diode
Answer: B
9. A light emitting diode is_________
(a) Heavily doped
(b) Lightly doped
(c) Intrinsic semiconductor
(d) Zener diode
Answer: A
10. Which of the following is not a characteristic of LED?
(a) Fast action
(b) High Warm-up time
(c) Low operational voltage
(d) Long life
Answer: B
11. Which of the following materials can be used to produce infrared LED?
(a) Si
(b) GaAs
(c) CdS
(d) PbS
Answer: B
12. The LEDs made with GaAs emit light in the_________
(a) Yellow region
(b) Infrared region
(c) Orange region
(d) Red visible region
Answer: B
13. What should be the band gap of the semiconductors to be used as LED?
(a) 0.5 eV
(b) 1 eV
(c) 1.5 eV
(d) 1.8 eV
Answer: D
14. The advantage of LED is___________
(a) Long life
(b) Fast on-off switching
(c) Low operating voltage
(d) All of the above
Answer : D
15. What is the bandwidth of the emitted light in an LED?
(a) 1 nm to 10 nm
(b) 10 nm to 50 nm
(c) 50 nm to 100 nm
(d) 100 nm to 500 nm
Answer: B
16. When forward biased, LED emits light because of___________
(a) Recombination of carriers
(b) Light generated in breaking the covalent bonds
(c) Light produced by collisions
(d) All of the above reasons
Answer : A
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